The present invention relates to mowing machines, particularly to mowing machines mounted on vehicles, and more particularly to a power driven mowing machine having a mower deck with object tracing capabilities which enables continuous mowing around objects, including objects having square corners.
Power driven mowing machines are extensively used for cutting grass in commercial, home and institutional applications. These mowing machines typically include a tractor-like motorized vehicle, with one or more mowers carried by the vehicle. Rotary lawn mowers carried by tractors or the like are frequently called "cutting decks" or "mowing decks", and each deck generally mows a swath along a path determined by the travel of the tractor. Where the deck is mounted on front, beneath, or behind the tractor, intermediate the front and rear wheels, it is substantially in line with the longitudinal axis or frame of the tractor, and the cutting path is substantially aligned with the travel path of the tractor. Typically, with tractor or vehicle mounted mowing or cutting decks, the cutting swath is wider than the wheels of the tractor.
In early vehicle mounted mowing decks, the maneuverability of the mowing decks depended on the maneuverability of the tractor and on the mounting location of the mowing deck. Thus, mowing of areas where the tractor could not safely or conveniently traverse, such as under shrubs or close to ditches, etc., mowing could not be carried out by the tractor driven mowers. Thus, hand mowing was required in these areas. This problem has been solved by the development of a movable or shiftable mowing deck which enables lateral movement of the mowing deck relative to the longitudinal direction of tractor movement. For example, U.S. Pat. No. 4,893,456 issued Jan. 16, 1990 provides a tractor mounted laterally shiftable mowing deck.
These early laterally shiftable mowing decks were controlled by the operator of the tractor or vehicle on which the mowing deck or decks were mounted. Thus, should an object in the mowing area not be seen by the operator, the mowing deck would strike the object causing damage to the mowing deck or cause flying material which could be hazardous. Also, if the mowing area included a tree or a post, for example, it was necessary for the operator to laterally move the mowing deck so that it could move around the tree, etc., which usually required the operator to slow the speed of the tractor to enable movement of the mowing deck sufficient to pass around the tree. In such application, a strip of unmown grass was usually on one side of the tree as the mowing deck could not be maneuvered fast enough to move the mowing deck around the edge of the tree. This problem was resolved, for example, by U.S. Pat. No. 5,425,224 issued Jun. 20, 1995 wherein a laterally movable, spring biased mowing deck was suspended under a tractor on a laterally extending mount such that the mowing deck was held by the spring in a predetermined location, and the mowing deck included a deck guard such that if the deck guard contacted a tree, for example, the mowing deck was laterally moved against the bias of the spring allowing the mowing deck to move around the tree and then back to its original predetermined position. U.S. Pat. No. 5,483,789 signed Jan. 16, 1996 provides a control system for a tractor mounted mowing deck which enables the deck to move vertically up or down, or moved laterally between a left limit and a right limit. Also, U.S. Pat. No. 5,771,672 issued Jun. 30, 1998 provided a system similar to that of above referenced U.S. Pat. No. 5,483,789 but also taught mounting the lateral support for the mowing deck or decks at an angle with respect to the longitudinal axis of the tractor to allow the operator greater maneuverability when passing between narrow objects or maneuvering around objects.
While these prior known laterally movable mowing decks have resolved many problems associated with tractor or vehicle mounted mowing applications, there has been a need for a tractor mounted power driven mowing deck which can continuously mow around square corners, such as cemetery headstones, grave markers, fenced areas, etc. In the past, it has been necessary for the operator to stop the mower after turning such a corner and then back up in order to mow the area just around the corner. Thus, in a cemetery, for example, considerable time is lost in mowing areas having square corners, or requiring the use of hand mowers or trimmers to cut that area just around each corner. While the lateral movable mowing deck of above referenced U.S. Pat. No. 5,425,224 enables mowing around trees, etc., it does not provide the capability to mow around square corners or square or rectangular cornered building or monuments because the movable mowing deck can only move laterally relative to the longitudinal axis of the tractor, and thus an area just around each corner of every corner of a square or rectangular area will be missed. Thus, there has been a need in the tractor (vehicle) mounted power driven mowing systems to enable mowing around square corners without missing an area or having to stop and back up to mow those areas just around the corners.
The present invention provides a solution to the above mentioned problem of mowing around square corners with a tractor mounted power driven mowing system. In this invention, the mowing deck mounting system is constructed to enable movement of the mowing deck both laterally and at an angle with respect to the longitudinal axis or frame of the tractor, whereby the mowing deck follows the contour of a building, monument, headstone, fence, etc. while the tractor is negotiating the corner, whereby the area just around the corner is mowed while the tractor continues around the corner at the same rate and then continues along that side of the building, monument, fence, etc. to the next corner which will be negotiated and mowed in the same manner. Thus, the present invention makes a substantial contribution to the state of the art tractor mounted power driven mowing systems.